Irrigation controllers are known for controlling the operation of an irrigation system in accordance with the passage of time. Most controllers operate a plurality of watering stations and will retain or store a watering program established by the user. This program typically allows the user to pick what days the sprinklers will operate, what time of day that irrigation will begin, and how long each station will operate. Some controllers allow multiple watering programs to be stored.
U.S. Pat. No. 5,262,936 discloses a microprocessor based controller in which the controller base unit has drivers and switches for controlling some number of irrigation stations that is less than the maximum number that can be controlled. The station handling ability of the controller can be expanded by plugging in additional modules with each module having drivers and switches for an additional number of stations. The modules when connected extend and are part of a serial bus structure in the controller. The modules known in this prior controller are quite large and when connected to the base unit of the controller take up considerable space exteriorly of the base unit, leading to problems in finding sufficient space to receive them all and in attaching all of the modules in a secure fashion.